The present disclosure relates generally to techniques that determine object characteristics using light emanating from the particles. More specifically, the techniques can use filter and/or optical arrangements to allow for the transmission, reflection, fluorescence, phosphorescence, photoluminescence, chemoluminescence and/or scattering of light with time variation, such as where the particles are moving relative to the filter and/or optical arrangements.
Various techniques have been proposed for using light emanating from objects. For example, U.S. Pat. No. 7,358,476 (Kiesel et al.) describes a fluidic structure with a channel along which is a series of sensing components to obtain information about objects traveling within the channel, such as droplets, cells, viruses, microorganisms, microparticles, nanoparticles, or other objects carried by fluid. A sensing component includes a set of cells that photosense a range of photon energies that emanate from objects. A processor can receive information about objects from the sensing components and use it to obtain spectral information. Additional techniques are described, for example, in U.S. Patent Application Publications 2008/0181827 (Bassler et al.) and 2008/0183418 (Bassler et al.), and in U.S. Pat. No. 7,547,904 (Schmidt et al.), U.S. Pat. No. 7,420,677 (Schmidt et al.), U.S. Pat. No. 7,701,580 (Bassler et al.), U.S. Pat. No. 7,894,068 (Bassler et al.), U.S. Pat. No. 8,373,860 (Kiesel et al.), and U.S. Pat. No. 7,386,199 (Schmidt et al.).